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A Midsummer Night at the Broad

Bruce Birren, Director of the Microbial Sequence Center and co-Director of the Genome Sequencing and Analysis Program, kicked off the Broad Institute’s 5th Annual Midsummer Nights' Science series. During his talk, entitled “Meet your Microbes,” Birren explained the research and goals of the Human Microbiome Project (HMP) to an audience of peers, public visitors and inquisitive children.

While the auditorium was a full-house, several quadrillion unnoticed guests also attended –our microbes. Birren explained that the human body is home to 10-times more microbial cells than human cells, meaning that each person carries approximately a hundred-trillion microbes. All of the microbes on and within the human body are collectively referred to as the human microbiome.

After stating that 400 microbial species inhabit the human mouth, Birren correctly predicted that a few people would suddenly want to brush their teeth. However, he encouraged the audience to think more positively about their microbes, as they are “intimately linked and influence our health and nutrition.” The genetic contribution from these organisms –totaling ~100,000 protein encoding genes– lead to favorable outcomes for humans, such as nutrient vitamin K and biotin acquisition. Thus, if we want to understand human biology and health, we need to understand our microbes.

Birren explained that one mission of the HMP is to generate the resources to describe human-associated microbial communities. Results from the HMP showed that the composition of microbial communities differs between bodily sites, over time and between individuals. Using next-generation sequencing, researchers sequenced the genomes of 178 newly described bacterial strains isolated from the human body, revealing 30,000 novel genes –a critical step towards understanding the human microbiome, which led Birren to say that he, “thinks of this research as exploring new worlds.”

Since human microbes likely provide essential or beneficial functions that are not encoded in our own genome, Birren said that some of the HMP’s current and future studies include determining how differences and dynamics of microbiomes are associated with health and disease. The Broad’s HMP has access to ~12,000 human microbiome samples, allowing for the analysis of community dynamics in microbial populations. The intestinal microbiome of healthy individuals and those suffering from ulcerative colitis and Crohn’s disease differed in composition, supporting the notion that the makeup of microbial communities is associated with various human diseases. Birren said that by examining the observations made from human microbiome studies in animal models, researchers can make a causative relationship between human microbiomes and various health outcomes, such as obesity and autoimmune diseases.

The take home message? For the first time, health is being examined in the context of our own genes, as well as those of our microbial communities within.